This is a bit straw man; no one ever said he wasn't exaggerating. The author isn't objecting to some precisely calibrated sentiment. He's disputing the premise:

This is a bit straw man; no one ever said he wasn't exaggerating. The author isn't objecting to some precisely calibrated sentiment. He's disputing the premise: that Tesla is singularly important, and that Edison is vastly overrated. The author is exaggerating or effect, but the effect sought is to make a case that isn't sarcastic, but rather quite sincere.